fix: [docker-host] Could not find ``gpg`` on some platform.

For instance debian buster (10) does not include a ``gpg`` binary by default.

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

precise/base-0k/hooks/install.d/20-kal-scripts.sh

@@ -17,6 +17,9 @@ if ! [ -e /etc/apt/sources.list.d/kalysto.org.list ]; then
 deb https://deb.kalysto.org no-dist kal-alpha kal-beta kal-main
 
 EOF
+    if ! type gpg >/dev/null; then
+        apt-get install -y --force-yes gnupg2 </dev/null
+    fi
     ## Include the GPG key
     wget -O - https://deb.kalysto.org/conf/public-key.gpg | apt-key add -